Story highlights

Protesters were in Mexico and as far away as Antarctica

Marches also took place in London, Paris, Cape Town and Sydney

(CNN)The Women's March extended beyond the United States, as similar protests cropped up around the world over women's rights and other issues the marchers fear could be under threat from Donald Trump's presidency.

Although the focus of the day was the Women's March on Washington, many people attended the hundreds of "sister marches" that occurred around the US and the globe.

Women and men in cities including Sydney, Berlin, London, Paris, Nairobi and Cape Town, marched in solidarity with the marchers in Washington and in opposition to the values they think Trump represents.

"Love rules in Antarctica," read one poster, held by a man bundled up on the snowy landscape in Paradise Bay.

"We are allies, not bystanders," read another sign, held by a woman posing in front of a glacier.

'Girl Power vs. Trump Tower'

Australia was the scene of the day's first major international march, with thousands joining an anti-Trump demonstration in downtown Sydney.

Marchers rally in Sydney in support of women's rights.

Organizers said as many as 5,000 people attended the protest at Martin Place; police estimated the number was closer to 3,000.

Chants from the crowd included "Women united will never be defeated" and "When women's rights are under attack, what do we do, stand up, fight back." Some carried banners with messages such as "Girl Power vs. Trump Tower" and "Dump the Trump."

A small group holds a pro-Trump rally Saturday in Australia's largest city.

A separate group of about 30 Trump supporters held a rally in Sydney. The police restrained some of them, blocking them from entering the same area as the Trump protest group.

Protest organizers in New Zealand's capital, Wellington, said about 700 people turned out there for a women's march. Marches were also held in Auckland, Christchurch and Dunedin.

Women's rights weren't the only issue on the agenda, with placards also bearing slogans to do with Brexit, nuclear weapons, workers' rights and lesbian, gay, bisexual and transgender rights.

Speakers at Trafalgar Square told the crowds at least 100,000 people had turned out. London's Metropolitan Police do not provide crowd estimates, but aerial footage showed large numbers of people gathered in the square.

London Mayor Sadiq Khan -- who before the US presidential election told CNN that Trump's views of Islam were "ignorant" -- posted a tweet encouraging Londoners to join the march and "show how much we value the rights every woman should have."